I. Field
The subject technology relates generally to communications systems and methods, and more particularly to systems and methods that provide protocols that enable communications transceivers to be tuned to an alternative channel in order to determine alternative frequencies or technologies that facilitate further communications in a mobile wireless communications setting.
II. Background
Wireless companies are constantly improving next-generation networks that combine voice and data on cellular networks, for example. Collectively, these companies have spent billions on licenses and equipment to provide a broad array of new data-centric services for customers. But emerging technologies could offer a leap past so-called third-generation systems just as they are beginning to emerge. One such technology is based on the IEEE 802.20 standard, a member of the 802 family that includes the better-known 802.11b, or Wi-Fi. The Wi-Fi LAN (local area network) standard has proliferated in recent years by offering broadband wireless connections for laptops and other mobile devices.
A new standard could change the direction of wireless networking, though. Whereas Wi-Fi and the newer 802.16 metro-area wireless broadband system are limited by the range of coverage areas—from a few hundred feet to 30 miles or so, respectively whereas 802.20 sits on existing cellular towers. It essentially promises the same coverage area as a mobile phone system with the speed of a Wi-Fi connection. This may account for why 802.20, or mobile broadband wireless access (MBWA), has generated interest regarding potential new applications.
One differentiating factor for these new applications is that they provide full mobility and nationwide coverage through cell-to-cell handoff with access to broadband speeds for any application. Thus, business travelers, for example, can access corporate networks while on the move and send information in real-time back to the office—just as if they were connected to the local area network at their respective office. In some cases, users get the same broadband Internet experience they have with a DSL or cable modem connection, but in a cellular mobile environment.
One aspect for employing mobile broadband wireless access technologies is the concept of an active set and related protocol for managing communications between an access terminal such as a cell phone and an access network such as a base station. A default Active Set Management Protocol provides the procedures and messages used by the access terminal and the access point to keep track of the access terminal's approximate location and to maintain the radio link as the access terminal moves between coverage areas of different sectors. In general, the Active Set is defined as a set of Pilots or Sectors with allocated MACID for an access terminal. The Active Set members can be synchronous or asynchronous with respect to each other. The access terminal can generally switch its serving Sector at any time among these Active Set member Sectors.
A Synchronous Subset of an Active Set consists of sectors that are synchronous with each other. Moreover, the subset is a maximal subset, i.e., generally all sectors that are synchronous with the sectors in this subset are contained in this subset. The different Synchronous Subsets ASSYNCH can be constructed using a last instance of an Active Set Assignment message, for example. Transmission from the access terminal to two different Synchronous Subsets of the active set is considered independent of each other. For example, the access terminal reports CQI to a Synchronous Subset of sectors independent of any other Synchronous Subset. One area that is of important concern is how communications are handed off between frequencies on a communications channel and/or between communications technologies that may be different between component of a given mobile broadband wireless access system.